Trends in colorectal cancer incidence in Sweden 1959-93 by gender, localization, time period, and birth cohort

Objectives: This study examined invasive colorectal cancer incidence-rates in Sweden from 1959 through 1993 (n = 134,643 cases). Methods: Age-standardized rates were calculated using the Swedish population in 1970 as a reference. Results: In right-sided colon cancer (ascending and transverse colon including right and left flexures), male age-standardized rates rose from 8.0 to 15.0 (1.8 percent annually, 95 percent confidence interval [CI] = 1.3-2.4) and female rates increased from 9.1 to 14.4 (1.5 percent annually, CI = 1.0-2.0). For left-sided colon cancer (descending and sigmoid colon), the rates have been stable recently. For rectal cancer, the rates among men rose from 18.8 to 23.0 and among women from 10.7 to 14.7. For both men and women, the relative risk (RR) of right-sided colon cancer had been increasing in successive generations, until leveling-off in those born after 1930. The RR of left-sided colon cancer had been almost constant for cohorts born before 1930 but steadily decreasing in later-born cohorts. The RR of rectal cancer was slightly increasing in successive cohorts. Conclusions: Changes in lifestyle or carcinogenic exposures during early life probably explain Swedish colorectal cancer incidence-trends better than improved diagnostic activities.     

Screening endoscopy and risk of colorectal cancer in United States men

Objectives: The purpose of this study was to describe the effect of screening endoscopy (sigmoidoscopy or colonoscopy) on colorectal cancer incidence and mortality. Methods: We used data from a prospective cohort study of 24,744 men aged 40 to 75 years in 1986, free from cancer and colon polyps, followed until 1994. The outcomes are diagnosis of colorectal cancer and death from colorectal cancer. Results: Screening endoscopy in 1986-87 was associated with a lower risk of all colorectal cancer (multivariate relative risk [RR]=0.58, 95 percent confidence interval [CI]=0.36-0.96); cancer in the distal colon or rectum (multivariate RR=0.40, CI=0.19-0.84); Dukes stage A&B (multivariate RR=0.66, CI=0.35-1.25); and Dukes stage C&D (multivariate RR=0.50, CI=0.20-1.26) colorectal cancer; and death from colorectal cancer (multivariate RR=0.56, CI=0.20-1.60), after adjusting for age and a wide range of colon cancer risk factors. Screening endoscopy in 1988-87 appeared to provide strong protection against distal stage C&D cancers (age-adjusted RR=0.16, CI=0.02-1.23) but no protection against proximal stage C&D cancers (age-adjusted RR=0.96, CI=0.32-2.91). Conclusions: This study provides strong evidence for a protective effect of screening sigmoidoscopy on colorectal cancer incidence and mortality and supports recommendations for screening sigmoidoscopy as an approach to colon cancer prevention.     

Dietary patterns and subsequent colorectal cancer risk by subsite: a prospective cohort study

In order to investigate the associations between dietary patterns and the risk of colorectal cancer by subsite in Japan, the baseline data from a population-based cohort study of 20,300 men and 21,812 women were analyzed. We conducted factor analysis and identified 3 major dietary patterns, "healthy," "traditional" and "Western," and calculated the factor scores of each pattern for individuals. During 10 years of follow-up, 370 colorectal cancer cases were identified. We found a positive association between the traditional pattern and colon cancer risk in women [rate ratio for highest quartile (RR) = 2.06; 95% CI = 1.10-3.84; p for trend = 0.11], but not in men. This positive association was slightly stronger for proximal colon cancer (RR = 2.07; 95% CI = 0.84-5.12) than for distal colon cancer (RR = 1.84; 95% CI = 0.75-4.50). After multivariate adjustment, the Western dietary pattern was also positively associated with colon cancer risk in females (RR = 2.21; 95% CI = 1.10-4.45), with the strongest associations being observed for females with distal colon cancer (RR = 3.48; 95% CI = 1.25-9.65). We did not observe any significant association between the healthy dietary pattern and colon cancer risk. For rectal cancer, no significant associations were found for the 3 dietary patterns. In conclusion, we found that the traditional and the Western dietary patterns were positively associated with colon cancer risk in females.     

Calcium intake and risk of colon cancer in women and men

BACKGROUND: Calcium has been hypothesized to reduce the risk of colon cancer, and in a recent randomized trial, calcium supplementation was associated with reduction in the risk of recurrent colorectal adenomas. We examined the association between calcium intake and colon cancer risk in two prospective cohorts, the Nurses' Health Study (NHS) and the Health Professionals Follow-up Study (HPFS). METHODS: Our study population included 87 998 women in NHS and 47 344 men in HPFS who, at baseline (1980 for NHS and 1986 for HPFS), completed a food frequency questionnaire and provided information on medical history and lifestyle factors. Dietary information was updated at least every 4 years. During the follow-up period (1980 to May 31, 1996 for the NHS cohort; 1986 to January 31, 1996 for the HPFS cohort), 626 and 399 colon cancer cases were identified in women and men, respectively. Pooled logistic regression was used to estimate relative risks (RRs), and all statistical tests were two-sided. RESULTS: In women and men considered together, we found an inverse association between higher total calcium intake (>1250 mg/day versus < or =500 mg/day) and distal colon cancer (women: multivariate RR = 0.73, 95% confidence interval [CI] = 0.41 to 1.27; men: RR = 0.58, 95% CI = 0.32 to 1.05; pooled RR = 0.65, 95% CI = 0.43 to 0.98). No such association was found for proximal colon cancer (women: RR = 1.28, 95% CI = 0.75 to 2.16; men: RR = 0.92, 95% CI = 0.45 to 1.87; pooled RR = 1.14, 95% CI = 0.72 to 1.81). The incremental benefit of additional calcium intake beyond approximately 700 mg/day appeared to be minimal. CONCLUSIONS: Higher calcium intake is associated with a reduced risk of distal colon cancer. The observed risk pattern was consistent with a threshold effect, suggesting that calcium intake beyond moderate levels may not be associated with a further risk reduction. Future investigations on this association should concentrate on specific cancer subsites and on the dose-response relationship.     

Incomplete pregnancies and risk of ovarian cancer (Washington, United States)

Because of the reduced risk of ovarian cancer related to prior full-term pregnancies, we sought to determine whether there was any association with a history of one or more incomplete pregnancies. White female residents of three counties in Washington State (United States) diagnosed with ovarian cancer during 1986–88 (n=322), and a random sample of control women selected from these same counties (n=426), were interviewed regarding their pregnancy and childbearing histories. Among women who had given birth to at least one child, an additional incomplete pregnancy was not associated with the risk of ovarian cancer (relative risk [RR]=1.1, 95 percent confidence interval [CI]=0.8–1.6, adjusting for age, oral contraceptive use, and number of births). For those who had never given birth, a somewhat smaller proportion of cases had a history of incomplete pregnancy than controls (RR=0.8, CI=0.4–1.7). In an analysis restricted to ever-pregnant women, a prior induced or spontaneous abortion was not found to be associated with the incidence of ovarian tumors (RR=1.0, CI=0.6–1.7, and RR=1.3, CI=0.8–1.9, respectively). Other studies of the possible relation between incomplete pregnancies and ovarian cancer generally have observed either a weak negative association or no association at all. It is possible that if incomplete pregnancies do affect the risk of ovarian cancer, their impact might be too small to be identified reliably through epidemiologic studies.This research was supported in part by a grant from the US National Cancer Institute (R35 CA39779), and by the Cancer Surveillance System of the Fred Hutchinson Cancer Research Center, which is funded by Contract No. N01-CN-05230 from the Surveillance, Epidemiology and End Results (SEER) program of the National Cancer Institute with additional support from the Fred Hutchinson Cancer Research Center.     

The distribution of cancer within the large bowel

The distribution of cancer of the anatomical sub-sites of the colon and rectum in Alameda County (California), Bombay, Denmark, Kingston and St Andrew (Jamaica), Miyagi Prefecture (Japan), New Zealand, Norway, Puerto Rico, Saskatchewan (Canada). Singapore, The South Metropolitan Cancer Registry (SMCR) (England), and Sweden were analysed. In this series, the highest rates for large-bowel cancer are found in North America and New Zealand; the lowest in the East (Japan, Bombay and Singapore) and the Caribbean, while intermediate rates prevail in Scandinavia and England. The pattern of sub-site distribution of the cancers throughout the large bowel is similar in areas of high and intermediate risk; namely, there is a decreasing incidence from ascending colon towards the descending colon with a sharp increase in incidence at the sigmoid colon, the rates for rectum being in turn higher than those for the sigmoid. In low-incidence areas, the general pattern is the same, but there may be a deficit of sigmoid cancers. This remains to be proved. Denmark shows a significant excess of lower rectum cancer, particularly in males. The age-standardized incidence rates for rectum cancer in this registry are higher than in any of the others, although the rates for other parts of the large intestine in Denmark are in the intermediate range. This finding should be exploited. With advancing age, the sex ratio for colon cancer as a whole shows a higher male risk; this male excess is, however, confined to the descending and sigmoid colon. The sex ratios for ascending and transverse colon cancer do not change with advancing age, while those for the sigmoid, and to a lesser extent the descending colon, do. Rectal cancer is commoner in males, the male preponderance becoming more pronounced after 65 years of age. For descending, sigmoid and rectal cancers, incidence increases more steeply with age in males than in females, the incidence-age curves on a log-log scale tending to have a downward curvature for the older age-groups. The slopes for ascending and transverse colon cancer do not differ between the sexes and their age-incidence curves have an upward curvature, particularly in women. It makes little difference to the incidence rates whether cancers of the recto-sigmoid are included in the rectum or the colon. The findings are discussed in the light of current aetiological theories. The results are consistent with the sub-site risk being related to the rate of transportation of colonic content. Transportation rates in the variety of risk situations need to be investigated, with particular attention being paid to the sigmoid in low-risk areas.     

Cervical carcinoma and reproductive factors: collaborative reanalysis of individual data on 16,563 women with cervical carcinoma and 33,542 women without cervical carcinoma from 25 epidemiological studies

The International Collaboration of Epidemiological Studies of Cervical Cancer has combined individual data on 11,161 women with invasive carcinoma, 5,402 women with cervical intraepithelial neoplasia (CIN)3/carcinoma in situ and 33,542 women without cervical carcinoma from 25 epidemiological studies. Relative risks (RRs) and 95% confidence intervals (CIs) of cervical carcinoma in relation to number of full-term pregnancies, and age at first full-term pregnancy, were calculated conditioning by study, age, lifetime number of sexual partners and age at first sexual intercourse. Number of full-term pregnancies was associated with a risk of invasive cervical carcinoma. After controlling for age at first full-term pregnancy, the RR for invasive cervical carcinoma among parous women was 1.76 (95% CI: 1.53-2.02) for > or => or =7 full-term pregnancies compared with 1-2. For CIN3/carcinoma in situ, no significant trend was found with increasing number of births after controlling for age at first full-term pregnancy among parous women. Early age at first full-term pregnancy was also associated with risk of both invasive cervical carcinoma and CIN3/carcinoma in situ. After controlling for number of full-term pregnancies, the RR for first full-term pregnancy at age <17 years compared with > or => or =25 years was 1.77 (95% CI: 1.42-2.23) for invasive cervical carcinoma, and 1.78 (95% CI: 1.26-2.51) for CIN3/carcinoma in situ. Results were similar in analyses restricted to high-risk human papilloma virus (HPV)-positive cases and controls. No relationship was found between cervical HPV positivity and number of full-term pregnancies, or age at first full-term pregnancy among controls. Differences in reproductive habits may have contributed to differences in cervical cancer incidence between developed and developing countries.     

A comparative case-control study of colorectal cancer and adenoma

We conducted a comparative case-control study of colorectal cancer and adenoma involving 221 cases with colorectal cancer, 525 cases with colorectal adenoma and 578 neighborhood controls. Daily vegetables intake was associated with lower risks of distal colon adenoma (relative risks (RR) = 0.59, 95% confidence interval (CI): 0.39-0.89) and rectal cancer (RR = 0.46, 95% CI: 0.25-0.84). Daily beans intake was associated with lower risk of colon adenoma (RR = 0.58, 95% CI: 0.37-0.91 for the proximal colon and RR = 0.63, 95% CI: 0.45-0.88 for the distal colon) and daily intake of seaweeds was associated with lower risk of rectal cancer (RR = 0.42, 95% CI: 0.22-0.82). Daily intake of fish and shellfish also showed an inverse association with the risk of colon adenoma (RR = 0.67, 95% CI: 0.45-0.99 for the proximal colon and RR = 0.70, 0.52-0.94 for the distal colon). Generally, intakes of animal or vegetable fat-rich foods, especially meats, were associated with decreases in risks of both adenoma and cancer, though the association of cancer was not statistically significant. Other than dietary factors, daily alcohol drinking was associated with an increased risk of adenoma in the proximal colon (RR = 1.95, 95% CI: 1.15-3.29) and ex-drinkers showed higher risks for colon adenoma and colorectal cancer. Sports or occupational activities and coffee drinking were inversely associated and family history of colorectal cancer was positively associated with the risk of both colorectal adenoma and cancer.     

Parity and other reproductive factors and risk of adenomatous polyps of the distal colorectum (United States)

Evidence for an effect of reproductive factors on colorectal carcinogenesis is inconsistent and little is known about their role in development of precursor adenomatous polyps. We evaluated the relation between reproductive factors and distal colorectal adenomas (n = 982) during14 years of follow up of 26,983 participants in the Nurses' Health Study(United States). The women were free of diagnosed cancer or polyps in 1980,underwent endoscopy 1980-94, and had reported on their parity, oral contraceptive (OC) use, and ages at menarche, first term-pregnancy, and menopause. We calculated relative risks (RR) and 95 percent confidence intervals (CI) using multiple logistic regression. Women with higher parity had an increased risk of adenomas of the distal colorectum (P trend = 0.004;6+ cf 0 parity: RR = 1.3, CI = 0.9-1.8) or distal colon (P trend = 0.002, RR= 1.7, CI = 1.2-2.6). This association was significantly stronger among women with a family history of colorectal cancer ( P interaction = 0.03); comparing6+ term-pregnancies with nulliparity, among those with a family history, the RR for distal colon adenoma was 3.2 (CI = 1.4-7.2), while among those without a family history, the RR was 1.3 (CI = 0.8-2.2). We observed no association for distal colorectal adenoma and age at menarche, age at first term-pregnancy, ever use of OCs, or menopausal status. Further work is needed to clarify the relation of parity with colon adenoma risk. This revised version was published online in July 2006 with corrections to the Cover Date.     

A Comparative Case-Control Study of Colorectal Cancer and Adenoma

We conducted a comparative case-control study of colorectal cancer and adenoma involving 221 cases with colorectal cancer, 525 cases with colorectal adenoma and 578 neighborhood controls. Daily vegetables intake was associated with lower risks of distal colon adenoma (relative risk (RR)=0.59, 95% confidence interval (CI): 0.39–0.89) and rectal cancer (RR=0.46, 95% CI: 0.25–0.84). Daily beans intake was associated with lower risk of colon adenoma (RR=0.58, 95% CI: 0.37–0.91 for the proximal colon and RR=0.63, 95% CI: 0.45–0.88 for the distal colon) and daily intake of seaweeds was associated with lower risk of rectal cancer (RR=0.42, 95% CI: 0.22–0.82). Daily intake of fish and shellfish also showed an inverse association with the risk of colon adenoma (RR=0.67, 95% CI: 0.45–0.99 for the proximal colon and RR=0.70, 95% CI: 0.52–0.94 for the distal colon). Generally, intakes of animal or vegetable fat-rich foods, especially meats, were associated with decreases in risks of both adenoma and cancer, though the association of cancer was not statistically significant. Other than dietary factors, daily alcohol drinking was associated with an increased risk of adenoma in the proximal colon (RR=1.95, 95% CI: 1.15–3.29) and ex-drinkers showed higher risks for colon adenoma and colorectal cancer. Sports or occupational activities and coffee drinking were inversely associated and family history of colorectal cancer was positively associated with the risks of both colorectal adenoma and cancer.     

Colorectal Cancer in Sweden a Descriptive Epidemiologic Study

In a register-based 19-year follow-up we studied the incidence rate of colorectal cancer in the Swedish 1960 census population. A total of 53 377 cases were identified: 28 003 men and 25 374 women. A U-shaped distribution of tumors in the large bowel was observed, with a minimum in the descending colon. Other findings were 1) An incidence gap between elderly men and women increasing with age and with distal direction in the large bowel; 2) An increase in the incidence of colorectal cancer with population density; 3) A higher incidence of colorectal cancer in the southwestern region than in the northern region and 4) A lower incidence of colon cancer among blue than among white collar workers and a lower incidence of colorectal cancer among never married men than among other men.     

Prospective study of fruit and vegetable consumption and incidence of colon and rectal cancers

BACKGROUND: Frequent consumption of fruit and vegetables has been associated with a reduced risk of colorectal cancer in many observational studies. METHODS: We prospectively investigated the association between fruit and vegetable consumption and the incidence of colon and rectal cancers in two large cohorts: the Nurses' Health Study (88 764 women) and the Health Professionals' Follow-up Study (47 325 men). Diet was assessed and cumulatively updated in 1980, 1984, 1986, and 1990 among women and in 1986 and 1990 among men. The incidence of cancer of the colon and rectum was ascertained up to June or January of 1996, respectively. Relative risk (RR) estimates were calculated with the use of pooled logistic regression models accounting for various potential confounders. All statistical tests were two-sided. RESULTS: With a follow-up including 1 743 645 person-years and 937 cases of colon cancer, we found little association of colon cancer incidence with fruit and vegetable consumption. For women and men combined, a difference in fruit and vegetable consumption of one additional serving per day was associated with a covariate-adjusted RR of 1.02 (95% confidence interval [CI] = 0.98-1.05). A difference in vegetable consumption of one additional serving per day was associated with an RR of 1.03 (95% CI = 0.97-1.09). Similar results were obtained for women and men considered separately. A difference in fruit consumption of one additional serving per day was associated with a covariate-adjusted RR for colon cancer of 0.96 (95% CI = 0.89-1.03) among women and 1. 08 (95% CI = 1.00-1.16) among men. For rectal cancer (total, 244 cases), a difference in fruit and vegetable consumption of one additional serving per day was associated with an RR of 1.02 (95% CI = 0.95-1.09) in men and women combined. None of these associations was modified by vitamin supplement use or smoking habits. CONCLUSIONS: Although fruits and vegetables may confer protection against some chronic diseases, their frequent consumption does not appear to confer protection from colon or rectal cancer.     

A prospective study of menopausal hormones and risk of colorectal cancer (United States)

The relation of colorectal cancer and its subsites with use ofmenopausal hormones was evaluated in the United States among 40,464postmenopausal women, 41 to 80 years of age, who initially volunteered for anationwide breast-cancer screening program and were followed for an averageof 7.7 years. Ever-use of menopausal hormones was not associated with risk oftotal colorectal cancers (relative risk [RR] = 0.99, 95 percent confidenceinterval [CI] = 0.79-1.2) or cancers of the colon (RR = 1.1, CI = 0.81-1.6)or rectum (RR = 1.1, CI = 0.59-1.9). Recent hormone users, however, had asmall nonsignificant reduction in risk of colorectal cancer (RR = 0.78, CI =0.55-1.1), which was most pronounced for distal colon (RR = 0.68, CI =0.29-1.6) and rectal tumors (RR = 0.64, CI = 0.24-1.7). No effect wasobserved for former hormone users, and risk generally did not vary by timesince last use, type of regimen, or duration of use. However, the reducedrisk for recent users was stronger for users of five or more years'duration. These data show some lowering of colorectal cancer risk amongrecent menopausal hormone users of long duration.     

Leisure-time physical activity patterns and risk of colon cancer in women

Although physical activity has been consistently associated with lower risk of colon cancer, many details of the relationship remain unclear. We assessed the relation between physical activity and risk of colon cancer in 79,295 women aged 40-65 who were free of cancer, ulcerative colitis and Crohn's disease and who reported their leisure-time physical activity in 1986; 547 cases were identified through 2002. Women who expended more than 21.5 metabolic equivalent hr/week of physical activity had a relative risk (RR) of colon cancer of 0.77 (95% CI 0.58-1.01), compared to women who expended <2 metabolic equivalent hr/week. The association was stronger for distal than proximal tumors. Among women whose only reported activity was walking, there was a decreased risk of colon cancer in women walking 1-1.9 hr/week (RR = 0.69, 95% CI 0.47-1.03) compared to those who did not walk. Results were similar for increased amounts of walking, but there was no evidence of a dose response relation. Among women who participated in moderate or vigorous activity, increasing hours of activity were also associated with a decreased risk of colon cancer (p for trend = 0.01); women exercising >4 hr/week had a 40% lower risk of colon cancer than those exercising <1 hr/week (RR = 0.56, 95%CI 0.33-0.94). Long-term physical activity was not associated with risk of colon cancer, but the number of cases was small. A significant inverse association exists between physical activity, including that of moderate intensity, such as walking, and risk of colon cancer in women that is more pronounced for distal tumors.     

alpha-fetoprotein levels in maternal serum during pregnancy and maternal breast cancer incidence

BACKGROUND: A full-term pregnancy is associated with a reduced risk of breast cancer, but the underlying biologic mechanism has not been elucidated. During pregnancy, maternal serum levels of alpha-fetoprotein, an estradiol-binding protein, rise sharply. In culture, alpha-fetoprotein inhibits the growth of estrogen-sensitive cells, including estrogen-sensitive breast cancer cells. Thus, we investigated whether a high level of alpha-fetoprotein in maternal serum during pregnancy is associated with a reduced risk of breast cancer. METHODS: From a population-based cohort of 42057 pregnant women in Denmark, enrolled in an alpha-fetoprotein-screening program from 1978 through 1996, we obtained a complete reproductive history, vital status, and a possible diagnosis of breast cancer (in 117 women) to the end of follow-up on September 1, 1998. RESULTS: During pregnancy, women with an alpha-fetoprotein level greater than or equal to the median value had a 41% lower risk of breast cancer than women with an alpha-fetoprotein level below the median value (relative risk [RR] = 0.59; 95% confidence interval [CI] = 0.41-0. 85). RRs for breast cancer by mother's age at childbirth were as follows: 29 years or younger, RR = 0.21 (95% CI = 0.08-0.56); 30-34 years, RR = 0.61 (95% CI = 0.32-1.14); 35-37 years, RR = 0.96 (95% CI = 0.49-1.89); and 38 years or older, RR = 0.71 (95% CI = 0.29-1. 75) (P for trend =.02). Further analyses suggested that high levels of alpha-fetoprotein were associated with a reduced incidence of aggressive disease. The most striking finding was that women with high levels of serum alpha-fetoprotein, compared with women with low levels of serum alpha-fetoprotein, showed a particularly reduced incidence of large tumors (>2 cm; RR = 0.24 [95% CI = 0.11-0.50]). CONCLUSION: A high level of alpha-fetoprotein in maternal serum during any pregnancy is associated with a low overall incidence of breast cancer and, in particular, with a low incidence of advanced breast cancer at diagnosis. This association appears particularly strong for a pregnancy occurring at a young age.     

Contraceptive methods and induced abortions and their association with the risk of colon cancer in Shanghai, China

267400 female textile workers in Shanghai, who were administered a questionnaire at enrollment into a randomised trial of breast self-examination between October 1989 and October 1991, were followed up until the middle of 2000. Based on the 655 women who developed colon cancer, rate ratios (RRs) were estimated and trends in risk assessed using Cox Proportional Hazards Models. Risk was increased in women who used oral contraceptives for over 3 years (RR=1.56, 95% Confidence Interval (CI) 1.01-2.40). A possible increase in risk was also observed in women who received progestational injections during pregnancy (RR=1.24, 95% CI 0.95-1.62), but not in relation to the use of injectable contraceptives. A possible reduction in risk was associated with tubal ligation (RR=0.86, 95% CI 0.71-1.03) and ever having had an induced abortion (RR=0.84, 95% CI 0.71-1.00). No trends in risk were observed in relation to the duration of hormonal contraceptive use or the number of induced abortions. Additional studies of the possible roles contraceptives may play in the aetiology of colon cancer in women at low risk of this disease are warranted.     

The risk of preterm birth and growth restriction in pregnancy after cancer

It is unclear whether cancer and its treatments increase the risk of adverse pregnancy outcomes. Our aim was to examine whether cancer survivors have higher risks of poor outcomes in pregnancies conceived after diagnosis than women without cancer, and whether these risks differ by cancer type and race. Diagnoses from cancer registries were linked to pregnancy outcomes from birth certificates in three U.S. states. Analyses were limited to the first, live singleton birth conceived after diagnosis. Births to women without a previous cancer diagnosis in the registry were matched to cancer survivors on age at delivery, parity, race/ethnicity and education. Log‐binomial regression was used to estimate risk ratios. Cervical cancer survivors had higher risks of preterm birth (Risk ratio = 2.8, 95% Confidence interval: 2.1, 3.7), as did survivors of invasive breast cancer (RR = 1.3, 95% CI: 1.1, 1.7) and leukemia (RR = 2.1, 95% CI: 1.3, 3.5). We observed a higher risk of small for gestational age (SGA) infants (<10% of weight for age based on a national distribution) in survivors of brain cancer (RR = 1.7, 95% CI: 1.1, 2.8) and extranodal non‐Hodgkin lymphoma (RR = 2.3, 95% CI: 1.5, 3.6). We did not see an increased risk of infants born preterm, low birth weight, or SGA in pregnancies conceived after ductal carcinoma in situ, thyroid cancer, melanoma, or Hodgkin lymphoma. While our results are reassuring for survivors of many cancers, some will need closer monitoring during pregnancy.     

Subsite-specific colorectal cancer incidence rates and stage distributions among Asians and Pacific Islanders in the United States, 1995 to 1999.

OBJECTIVE: This study examined subsite-specific colorectal cancer incidence rates and stage distributions for Asians and Pacific Islanders (API) and compared the API data with data for Whites and African Americans. METHODS: Data included 336,798 invasive colorectal cancer incident cases for 1995 to 1999 from 23 population-based central cancer registries, representing about two thirds of API population in the United States. Age-adjusted rates, using the 2000 U.S. standard population, and age-specific rates and stage distributions were computed by anatomic subsite, race, and gender. All rates were expressed per 100,000. SEs and rate ratios were calculated for rate comparison. A significance level of 0.05 was used for all analyses. RESULTS: Overall, age-adjusted colorectal cancer incidence rates were significantly lower in API than in Whites and African Americans across anatomic subsites, particularly for proximal colon cancer in which rates were 40% to 50% lower in API males and females. Exception to this pattern was the significantly (10%) higher rectal cancer incidence rate in API males than in African American males. The incidence patterns by anatomic subsite within API differed from those of Whites and African Americans. Among API, the rate of rectal cancer (19.2 per 100,000) was significantly higher than the rates of proximal (15.2 per 100,000) and distal (17.7 per 100,000) colon cancers in males, with little variations in rates across anatomic subsites in females. In contrast, among White and African American males and females, proximal colon cancer rates were over 25% higher than the rates of distal colon and rectal cancers. Increases in age-specific rates with advancing age were more striking for proximal colon cancer than for distal colon and rectal cancers in Whites and African Americans, while age-specific rates were very similar for different subsites in API with parallel increases with advancing age, especially in API males. Similar to Whites and African Americans, in API, proximal colon cancers (32% to 35%) were also less likely to be diagnosed with localized stage compared with distal colon (38% to 42%) and rectal (44% to 52%) cancers. CONCLUSION: The patterns of subsite-specific colorectal cancer incidence in API, especially API males, differ from those of Whites and African Americans. Similar to Whites and African Americans, lower percentage of localized disease in API for proximal colon cancer than for distal colon and rectal cancers was also observed.     

Physical activity and risk of cancers of the colon and rectum: an Italian case-control study

We investigated the relationships between risk of colon and rectal cancers and physical activity in both sexes at different ages by a case-control study conducted between 1991 and 1996 in six Italian centres. Cases were 1225 patients (688 men, 537 women) below the age of 75 with colon cancer and the controls included 4154 patients (2073 men, 2081 women) admitted to hospital for acute, non-neoplastic conditions. We also analysed 722 cases of rectal cancer. Compared with the lowest level of occupational physical activity at 30-39 years old the odds ratios (OR) for the highest level were 0.64 (95% confidence interval, CI 0.44-0.93) in men and 0.49 (95% CI 0.33-0.72) in women. The inverse association in both sexes was similar at 15-19 and 50-59 years old. No association was found in either sex for leisure-time physical activity. For both sexes the inverse relationship between occupational physical activity at 30-39 years old and colon cancer risk was not significantly heterogeneous across strata of selected covariates, and for ascending, transverse, descending and sigmoid colon. Rectal cancer risk was not associated with any measure of physical activity (OR = 1.32 for men and 0.88 for women for the highest level of occupational physical activity at 30-39 years old compared with the lowest). This study confirms that occupational physical activity is protective against colon, but not against rectal cancer.     

Large bowel cancer in women in relation to reproductive and hormonal factors: a case-control study

A community-based case-control study of the effect of reproductive factors on risk of large bowel cancer in Australia is described. The study involved 155 cases (99 colon cancer, 56 rectal cancer) and 311 controls who were interviewed with regard to pregnancies and their outcomes, lactation, menstrual history, and oral contraceptive (OC) use. Increasing parity was associated with a decreasing risk of colon cancer; para 0, relative risk (RR)=1; para 1-2, RR=0.9, 95% confidence interval (CI)=0.4-1.8; para greater than or equal to 3, RR=0.4, 95% CI=0.2-0.8; later age at first live birth (AFLB) was associated with increasing risk (AFLB less than or equal to 21 yr, RR=1; 22-25 yr, RR=2.3, 95% CI=1.0-5.5; greater than or equal to 26 yr, RR=2.7, 95% CI=1.2-6.2). These effects were independent of each other. Parity appeared to exert its predominant effect on risk of cancer of the right colon. OC use was more common among controls than cases (RR=0.5; 95% CI=0.3-1.2 for ever vs. never users) and showed a dose-response effect in multiple logistic analysis. The pattern of point-estimate RR for rectal cancer was largely congruent with those for colon cancer but was not significantly different from 1.0.